This present invention relates generally to automatic record playing apparatuses having tone arm position detecting devices, and more particularly to a record playing apparatus capable of automatically playing a record disc by using an output signal produced by the detecting device which output signal is a signal corresponding to the position of the tone arm which is detected by the tone arm detecting device.
In general, when a record disc contains a number of pieces of music on the same side thereof, two of consecutive pieces are separated from each other by a coarse groove portion, which will be referred to as a separation band, at which no information has been prerecorded. These separation bands are provided not only for providing a short interval between pieces of music but also for making it easy to place the stylus of the phonograph cartridge or pickup so that a specific piece of music may be selectively played back. However, in order to succeed in such selection and positioning of the stylus onto a separation band just prior to a desired piece of music the user or operator of the record playing apparatus has to be skilled. Namely, since the separation band has a relatively narrow width, the stylus might be positioned onto a wrong position, i.e. a fine-groove portion, when the pickup arm is manipulated manually, and furthermore, there is a possibility that the stylus and/or the record grooves might be damaged.
Recently, new programmable automatic record playing apparatuses have been developed to remove the above mentioned inconveniences. Namely, according to these known playing apparatuses the pickup arm is automatically positioned in accordance with a command signal produced in view of the pickup arm position detected by means of a photosensor so that pieces of music, which have been programmed, will be reproduced in a sequence. However, the photosensor for detecting the position of the arm is incorporated in or built in the pickup shell or casing.
Therefore, it is impossible to replace such a pickup cartridge with a desired one. Furthermore, the above-mentioned known automatic record playing apparatuses are not equipped with a memory for storing distances between the separation bands, and therefore, when a plurality of programmed pieces of music are reproduced, in a sequence the pickup arm has to be returned to the peripheral portion of the disc each time prior to selecting the next piece. Since the pickup arm returns to the outer portion of the disc each time on selection of a piece of music, prior to a correct positioning of the arm onto a programmed separation band, namely the pickup arm moves back and forth, it is time consuming. In other words, a relatively long access time is required in the known programmable automatic record player.
Accordingly, the inventor of the present invention has already proposed a programmable automatic record playing apparatus capable of selecting pieces of recorded information within a short access time, and accurately positioning and lowering the stylus of the pickup cartridge to a desired position.
The present invention has been developed in order to provide a tone arm position detecting device suitable for this type of programmable automatic record playing apparatus.